The present invention relates to a method for providing communication information regarding a communication unit of a user via a communication system assigned to the unit. Therefore, a communication unit refers to the entirety of the communication devices available to a user, such as a mobile telephone, a fixed network telephone, a portable computer or a stationary computer. The present invention also concerns a communication system and a communication device for carrying out the above-described method.
Conventional applications, particularly according to the GSM (Global System for Mobile communication) standard, are implemented without knowledge of the state of the communication partner. A call is effected, a short message or SM within the framework of the SMS (short message service) or a multimedia message of the MMS (multimedia message service) is sent without the initiator (calling subscriber or SMS/MMS sender) having knowledge about the status of the receiver (called subscriber or SMS/MMS addressee); i.e., particularly irrespective of whether or not the user terminal of the receiver is actually switched on. It is, therefore, disadvantageous that the initiator cannot be certain whether or not the receiver, for example, actually receives an urgent message.
In Japan, within the framework of i-mode, a service is used in the cellular phone network environment with the designation “e-mail”, but which has nothing to do with the Internet e-mail. This service is used in the same way as chat or instant messaging (instant messaging referring to the immediate exchange of text messages via instant messaging and presence services that is undertaken on the basis of presence information) see RFC 2778 “A Model for Presence and Instant Messaging”, M. Day, J. Rosenberg, H. Sugano, February 2000 (http://www.ietf.org/rfc/rfc2778.txt?number=2778) and RFC 2779 “Instant Messaging/Presence Protocol Requirements”, M. Day, S. Aggarwal, G. Mohr, J. Vincent, February 2000 (http://www.ietf.org/rfc/rfc2779.txt?number=2779)|. This is a presence-oriented communication services that allows the user to exchange messages and presence notifications under a completely individual standard. Therefore, the communication partners selected by a user are listed on the display of the user mobile telephone with its corresponding status. The user can experience the current status for each selected subscriber; for example, whether or not the i-mode user can be reached via his/her mobile telephone. Icons that show emotion (happy, busy, etc.) are also exchanged between users.
Disadvantageous for such a communication service is the fact that, in the case of the user receiving the information that his/her selected subscriber is not available via his/her mobile telephone at present, it is impossible to reach the selected subscriber via an alternative communication medium or other communication service; for example, in order to send him/her an urgent message.
Therefore, an object of the present invention is to provide a method and device by which the accessibility of a selected subscriber is improved.